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Ram Air Cooling

Over the years there have been many ideas/inventions designed to assist the engine cooling of the vespa. The Vespa Labs community have done a few tests, primarily on the famous "highwayman" device made by Paul.  Please add any experiments here.

The general conclusion was that although ramming air into the existing fan setup reduced  cylinder head temperature, it is not always desireable to reduce temperature. It is also possibly a simple cover up for incorrect jetting/air leak etc.

1. highwayman: ( Notes in Lab Area

300px-Highwayman_Mark_I.jpg

2. 80's plastic aftermarket fan cowl with built in ram. This one defies the physics behind the stock cooling system. The ram cut out is at the bottom, and therefore outer edge, of the cowl. The problem here is that the fan works is by creating an outward ait pressure which is trapped and channelled up and over across the head. The cutout would release this air pressure this reducing cooling. It looks cool though and sometimes that is important. I'd like to credit the logic behind this argument but I cant remember if it was Jeremy or Paul.

300px-80s_Air_Scoop_Technology.jpg

3. found a pic on the web of someone elses efforts. I would say this would effectively reduce engine temperature at mid to high speed.

http://img65.imageshack.us/img65/7898/p1020405kc9.jpg

Alternative

Changing the timing in relation to heat may be an easy auto-protection mechanism. Using variable timing, retard the timing automatically if the engine overheatsby reading a CHT. Obviously this will impact power (but not as much as heat seize).

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Paul McIntosh,
Mar 25, 2015, 12:43 AM
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Paul McIntosh,
Mar 25, 2015, 12:42 AM
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Paul McIntosh,
Mar 25, 2015, 12:43 AM
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Paul McIntosh,
Mar 25, 2015, 12:43 AM
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